Data storage systems typically store information on surfaces of storage media. When data are stored on a storage medium they are generally stored in a set of data tracks. The tracks on the medium surface are typically divided into sectors. Sectors are the basic units of data storage on a medium surface. A sector is a storage segment along the length of a track.
User data are stored in data sectors, while servo data are stored in servo sectors that are inserted between data sectors along each track. Information that is stored in servo sectors is utilized by a servo system in the data storage system. Conventional servo systems extract head position information from the servo sectors such that the head is positioned at or very close to a track center of a track before user data are written to a data sector or read back from the data sector.
Conventional data storage systems assume that a head will not significantly stray from the center or approximately near the center of a track from one servo sector to the next. Then, the data storage system processes the user data in the data sectors assuming that the head position is correct. Such an assumption requires tight constraints on data fields within each servo sector.